Enhancement of Er^3+ upconverted luminescence in Er^3+: Au-antimony glass dichroic nanocomposites containing hexagonal Au nanoparticles

Dichroic Er3+:Au-antimony glass nanocomposites are synthesized in a new reducing glass (dielectric) matrix (mol%) K2O-B2O3-Sb2O3 (KBS) by a single-step melt-quench technique involving selective thermochemical reduction principle. Transmission electron microscopic images reveal hexagonal Auo nanoparticles having major axes about 9-23 nm. Dichroic behavior arises due to hexagonal Auo nanoparticles of aspect ratio 1.2-1.3. Auo nanoparticles of concentration of 0.03 wt%(4.1×1018 atoms/cm3) drastically enhances the intensity (2-5 folds) of both 536 (S3/24-->I15/24, green) and 645 (F9/24-->I15/24, red) nm emission bands of Er3+. Local field enhancement induced by Auo surface plasmon resonance (SPR) and energy transfer from fluorescent Auo-->Er3+ ions are found to be responsible for enhancement while, at very high Au concentration, energy transfer from Er3+-->Auo and optical reabsorption due to Auo SPR result in quenching.